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Re: A reprise.....how to build a gantry for a chain falls....

To: "Gerald Brazil" <gerrybraz@voyager.net>
Subject: Re: A reprise.....how to build a gantry for a chain falls....
From: David Scheidt <dmschei@attglobal.net>
Date: Fri, 27 Feb 2004 22:06:35 -0500
On Feb 27, 2004, at 7:00 PM, Gerald Brazil wrote:

>
> Thanks to everybody who gave me a lot of good suggestions.
>
> I rejected the idea of wood because I wasn't confident that I would be
> able to build it well enough. I then explored making one out of steel.
> When I visited the place where I buy steel, I learned that you can't 
> get
> a nice slip fit in square tube because of the weld seam on the inside.
> If you get an inner tube that will slide, it is a sloppy fit.

Clearly, you need a better steel supplier.  There are such things as 
DOM and HRS (hot rolled seamless) square tubes.  Neither is allowed to 
have evidence of an inside seam.  They cost more than stuff that might, 
or might not, have weld flash on the inside, but they exist.  
Incidentally, good quality square tube has the welded seam on the 
middle of a flat, not a corner.  It's formed from round tube, using 
rollers on all four sides.  Cheaper stuff (good enough for lots of 
structural stuff, though) is made by forming a flat into a square and 
welding the corner where the two edges meet.

Regards,

David






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